The invention relates to an activation system, a remotely triggerable circuit system containing this system, and to respective operating methods.
Electric circuits, which are not connected to a power supply system, e.g. radio identity disks or radio access cards, tickets, etc. (smart cards) require extremely low energy consumption. Constant operation would very quickly drain the batteries.
The circuits are therefore conventionally maintained in a very power-saving, inactive state and only activated for short periods as required. Activation is effected to date by means of a radio signal, which is received in the battery-operated device, rectified and used for activation. Activation is then generally triggered when the rectified signal exceeds a defined threshold value.
One problem with this conventional method is the often inadequate range of the activation signals, which is due in particular to the low level of efficiency of rectifier diodes at low voltages. A further problem is that the activation system responds to all signals in a specific frequency range, including interference signals, as no “intelligence” has been prompted before activation—resulting in unwanted activation of the circuit and therefore premature draining of the batteries.
FIG. 3 outlines the principles of activation according to the prior art.
An activation transmitter ST1 sends an activation signal SIGA to a conventional activation system ST2. The activation system ST2 comprises a directly operating rectifying circuit, which rectifies the activation signal SIGA and uses it directly for its operation.
A device is known from WO 00/43802, with which radiation at the site of a coding element is converted using a converter to a secondary energy form, which is buffered. The stored secondary energy is then fed to a non-linear element, which is a spark discharge gap.
An ID tag is known from EP 0 467 036 A2, which is maintained by means of an activation or wake-up circuit at constant low output. The activation circuit is activated by a received signal, which is first analyzed by a microprocessor.